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fix(core): handle stateless MCP wrapper transport correlation #20293

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logaretm merged 2 commits into from
Apr 16, 2026
+98 −9
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fix(core): handle stateless MCP wrapper transport correlation #20293

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c4271fc
fix(core): handle stateless MCP wrapper transport correlation
logaretm Apr 14, 2026
5c60a74
fix(core): align MCP session metadata lookup for wrappers
logaretm Apr 14, 2026
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12 changes: 6 additions & 6 deletions packages/core/src/integrations/mcp-server/transport.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
if (isInitialize) {
try {
initSessionData = extractSessionDataFromInitializeRequest(message);
storeSessionDataForTransport(this, initSessionData);
storeSessionDataForTransport(transport, initSessionData);
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} catch {
// noop
}
Expand All @@ -65,7 +65,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
});
}

storeSpanForRequest(this, message.id, span, message.method);
storeSpanForRequest(transport, message.id, span, message.method);

return withActiveSpan(span, () => {
return (originalOnMessage as (...args: unknown[]) => unknown).call(this, message, extra);
Expand Down Expand Up @@ -114,14 +114,14 @@ export function wrapTransportSend(transport: MCPTransport, options: ResolvedMcpO
if (message.result.protocolVersion || message.result.serverInfo) {
try {
const serverData = extractSessionDataFromInitializeResponse(message.result);
updateSessionDataForTransport(this, serverData);
updateSessionDataForTransport(transport, serverData);
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} catch {
// noop
}
}
}

completeSpanWithResults(this, message.id, message.result, options, !!message.error);
completeSpanWithResults(transport, message.id, message.result, options, !!message.error);
}
}

Expand All @@ -139,8 +139,8 @@ export function wrapTransportOnClose(transport: MCPTransport): void {
if (transport.onclose) {
fill(transport, 'onclose', originalOnClose => {
return function (this: MCPTransport, ...args: unknown[]) {
cleanupPendingSpansForTransport(this);
cleanupSessionDataForTransport(this);
cleanupPendingSpansForTransport(transport);
cleanupSessionDataForTransport(transport);
return (originalOnClose as (...args: unknown[]) => unknown).call(this, ...args);
};
});
Expand Down
32 changes: 32 additions & 0 deletions packages/core/test/lib/integrations/mcp-server/transportInstrumentation.test.ts
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Expand Up @@ -880,6 +880,38 @@ describe('MCP Server Transport Instrumentation', () => {
expect(mockSpan.end).toHaveBeenCalled();
});

it('should correlate spans correctly for stateless wrapper transports', async () => {
const { wrapper, inner } = createMockWrapperTransport('stateless-wrapper-session');
inner.sessionId = undefined;

const mockMcpServer = createMockMcpServer();
const wrappedMcpServer = wrapMcpServerWithSentry(mockMcpServer);

await wrappedMcpServer.connect(wrapper);

const mockSpan = { setAttributes: vi.fn(), end: vi.fn() };
startInactiveSpanSpy.mockReturnValue(mockSpan as any);

inner.onmessage?.call(
inner,
{
jsonrpc: '2.0',
method: 'tools/call',
id: 'stateless-wrapper-req-1',
params: { name: 'test-tool' },
},
{},
);

await wrapper.send({
jsonrpc: '2.0',
id: 'stateless-wrapper-req-1',
result: { content: [{ type: 'text', text: 'success' }] },
});

expect(mockSpan.end).toHaveBeenCalled();
});

it('should handle initialize request/response with wrapper transport', async () => {
const { wrapper } = createMockWrapperTransport('init-wrapper-session');
const mockMcpServer = createMockMcpServer();
Expand Down
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